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The Fascinating Fire Ant: How These Insects Survive the Unthinkable


If you’ve switched on your TV at any point since late August, you’ve  heard about Hurricane Harvey. The tempest ravaged eastern Texas and brought nearly 40 inches of rain in four days. It completely flooded Houston and caused billions of dollars in damages. Pictures of devastation dominated the news cycle for weeks. Amidst the heartbreaking stories, there were also some strange occurrences. Most intriguing were those featuring mysterious debris gliding through the streets of Houston and other communities. Upon further inspection, the floating debris turned out to be balls of fire ants struggling to survive. How in the world were mere ants able to do this? It turns out that fire ants are a far more resilient species than most think.

fire-ant

Survival Instinct

Fire ants are truly fascinating creatures. Their ability to survive in all conditions is uncanny. Though blind to everything but their immediate surroundings, they are able to work together to accomplish some truly remarkable feats.

  • They are able to resist some insecticides. Poisoning their mounds does not always necessarily kill them all.
  • They can build large towers to act as makeshift shelters until they find more suitable conditions.
  • They can band together to form buoyant rafts that survive for weeks on end.

They need these highly adaptable survival skills because certain fire ants are an invasive species. Accidentally brought in from South America, this particular ant has spread through the part of North America, Australia, and several Caribbean and Asian countries.

Solenopsis invicta, known as the red imported fire ant (RIFA) in the United States, wreaks havoc on the communities in which they’re found. The US Food and Drug Administration estimates that the nation spends over $5 billion on treatment, control in infested areas, and damage annually.

Invasive fire ants thrive in urban areas. They build nests in backyards, golf courses, and other recreational areas. Their presence proves truly damaging in these urban areas because of their attraction to electricity. Ants can destroy a wide array of electrical equipment, causing headaches for local business owners.

Agriculture suffers at the antennae of these non-native pests, too. Fire ants destroy crops, threaten orchards and pastures, and kill off pest-controlling predatory insects. Soybean farmers in the southeastern United States in particular complain that fire ants can have a big impact on crop yields.

How Did They Make a Raft?

Fire ants originally came from the wetlands of Brazil where it floods several times a week. This ability to avoid drowning is vital to a colony’s survival. They must rely on one another in a way that few other insect species do.

In the wake of Hurricane Harvey, you could find evidence of this survival instinct everywhere. Hundreds of fire ant colonies floated throughout affected areas in Texas and Louisiana. There were reports of people trying to break apart or drown the ants, with damaging results. Anyone trying to sink one of the rafts only agitated the insects, causing them to start crawling up whatever they were prodded with.

Fire ants’ bodies, as well as those of countless other insects, partially repel water (a characteristic known as “hydrophobic” in scientific terms). This characteristic keeps the insects from sinking. When submerged, their bodies trap a layer of air to prevent them from sinking. These trapped bubbles allow ants to survive when partially submerged.

If one ant is mildly hydrophobic, an entire colony is borderline unsinkable. The more of them you get together, the more effective their ability to repel water. When you push down on one of the rafts, surface tension pushes the water away with it. Even if you do somehow manage to push them down, the ants take a massive air bubble along with them. A floating colony is able to survive on the water for weeks.

hydrophobic-insects

Scary as the prospect of venomous ant flotillas bobbing in floodwaters may be, there is a way to destroy them. Using something like dish soap weakens the grip the ants have on one another. It also prevents their bodies from forming air bubbles when submerged. Studies have shown that spraying a floating colony with a mildly soapy solution killed nearly all  the ants within ten minutes.

Though tempting when faced with a novel phenomenon in the wild, don’t put yourself in danger. For your safety, and for the safety of those around you, don’t mess with fire ant rafts. Let them be and admire their resilience; and, admire the resilience of those millions of people affected by hurricanes Harvey, Irma, and Maria. If you can, make a donation to support relief efforts in communities devastated by the storms.


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